Baby marmosets learn to speak in a similar way to human infants, new research has found.

A baby's babbles start to sound like speech more quickly if they get regular vocal feedback from adults.

And researchers have found the same type of feedback speeds up the vocal development of infant marmoset monkeys.

The study is the first assured evidence of 'call and response' learning in primates besides humans.

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A baby's babbles start to sound like speech more quickly if they get regular vocal feedback from adults. And researchers have found the same type of feedback speeds up the vocal development of infant marmoset monkeys (stock image)

CALL AND RESPONSE LEARNING

The researchers said that call and response vocal learning may be linked to the idea that an infant that produces adult-like sounds more quickly is more likely to receive care.

The faster the infants can learn, the more likely it is to receive care and so the more likely it is to survive in the wild.

Much like in human social groups, marmosets work in a cooperative environment where multiple members of a group can provide care to infants in addition to the parents.

'So it's not only this process of learning that's similar to humans; the whole reproductive strategy is similar to humans,' study lead author Professor Asif Ghazanfar said.

Even though marmosets can't 'talk' in the same way humans do, understanding marmoset communication may help us understand the evolution and development of human speech.

'We wanted to find out whether the idea that monkeys don't do any learning during their vocal development is actually true,' said study lead author Professor Asif Ghazanfar, a psychologist at Princeton University.

'So we picked a species that we know really relies on vocalisations as its primary social signals.

'What we found in marmoset vocal development very closely parallels pre-linguistic vocal development in humans.'

Although marmoset vocal calls are not as complex as human language systems, vocal development in both species begins with infants making random sounds.

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To find out whether the same principle held true for marmosets, Professor Ghazanfar and his colleagues set up an experiment using pairs of fraternal twin marmosets, small, highly social monkeys from South America.

Starting from the day after the marmosets were born, the researchers would separate the infants from the adult marmosets for 40 minutes each day.

In the first 10 minutes, they recorded the noises that the infant marmosets made while sitting alone.

Even though marmosets can't 'talk' in the same way humans do, understanding marmoset communication may help us understand the evolution and development of human speech (stock image)

Then, for the next half hour, the researchers gave the young marmosets contingent feedback in the form of audio playbacks of the parent's calls.

One twin in each pair got consistent feedback, mirroring what a young marmoset would receive from an especially attentive parent.

The other twin got less consistent feedback on their vocalisations.

The team repeated these experiments up until the infants were 2 months old, roughly the equivalent of 2 years old in marmoset years.

MONKEYS TAKE TURNS TO TALK

They may not be known for their good manners, but it seems that monkeys are actually masters of courteous chat.

Marmosets take turns to ‘talk’ and can keep a conversation going for up to half an hour, according to research.

They also don’t speak over or interrupt each other and are as polite to relative strangers as they are to monkeys they are normally housed with.

The US researchers placed pairs of marmosets in a room and recorded their calls.

The monkeys clearly took turns in calling out, with the second waiting around five seconds to respond, and engaged in lengthy exchanges.

Researcher Asif Ghazanfar, of Princeton University in New Jersey, said: ‘We were surprised at how reliably the marmoset monkeys exchanged their vocalisations in a co-operative manner, particularly since in most cases they were doing so with individuals they were not pair-bonded with.

‘This makes what we found much more similar to human conversations and very different from the co-ordinated calling for birds, frogs or crickets, which is linked to mating or territorial defence.’

He said the monkeys may find the pattern of conversation relaxing.

The research showed that even relative strangers engaged in conversations of up to half an hour.

Even though these sessions lasted less than an hour each day, infant marmosets that received lots of contingent feedback developed adult-sounding calls more rapidly than their siblings.